Hydrocarbon injection through small pore cu-zeolite catalyst

Abstract

A system comprising a hydrocarbon source, a downstream catalyst, and an SCR catalyst, wherein the SCR catalyst is located between the hydrocarbon source and the downstream catalyst, and wherein the downstream catalyst comprises a catalyst selected from the group consisting of a diesel oxidation catalyst (DOC), a diesel exotherm catalyst (DEC), a catalyzed soot filter (CSF), a NOx absorber, a selective catalytic reduction/passive NOx adsorber (SCR/PNA), a cold-start catalyst (CSC) or a three-way catalyst (TWC).

We claim: 
     
         1 . An exhaust treatment system comprising
 a hydrocarbon source,   a downstream catalyst comprising a filter, and   an SCR catalyst,   wherein the SCR catalyst is located between the hydrocarbon source and the downstream catalyst.   
     
     
         2 . The system of  claim 1 , wherein the SCR catalyst comprises a small pore molecular sieve. 
     
     
         3 . The system of  claim 1 , wherein the SCR catalyst comprises a small pore Cu zeolite. 
     
     
         4 . The system of  claim 1 , further comprising an ammonia slip catalyst (ASC). 
     
     
         5 . The system of  claim 1 , comprising a substrate comprising an inlet end and an outlet end, a first zone and a second zone, where the first zone comprises an ammonia slip catalyst (ASC) comprising a platinum group metal and the SCR catalyst, and the second zone comprises the downstream catalyst, where the first zone is located upstream of the gas flow relative to the second zone. 
     
     
         6 . The system of  claim 5 , where the first zone and the second zone are located on the same substrate and the first zone is located on the inlet side of the substrate and the second zone is located on the outlet side of the substrate. 
     
     
         7 . The system of  claim 5 , wherein the substrate comprises a first substrate and a second substrate, where the first zone is located on the first substrate and the second zone is located on the second substrate and the first substrate is located upstream of the second substrate. 
     
     
         8 . The system of  claim 5 , where the first zone comprises
 a bottom layer comprising the ASC, and   a top layer comprising the SCR catalyst,   wherein the top layer is located over the bottom layer.   
     
     
         9 . The system of  claim 5 , where the second zone comprises a blend of an oxidation catalyst and a second SCR catalyst. 
     
     
         10 . The system of  claim 5 , where the platinum group metal comprises platinum, palladium or a combination of platinum and palladium. 
     
     
         11 . The system of  claim 1 , wherein the downstream catalyst comprises a catalyst selected from the group consisting of a diesel oxidation catalyst (DOC), a diesel exotherm catalyst (DEC), a catalyzed soot filter (CSF), a NOx absorber, a selective catalytic reduction/passive NOx adsorber (SCR/PNA), a cold-start catalyst (CSC) or a three-way catalyst (TWC), and combinations thereof. 
     
     
         12 . The system of  claim 1 , wherein the downstream catalyst comprises a DOC, a CSF, or combinations thereof. 
     
     
         13 . The system of  claim 1 , comprising an oxidation catalyst between the SCR catalyst and the downstream catalyst. 
     
     
         14 . The system of  claim 1 , comprising DOC between the SCR catalyst and the downstream catalyst. 
     
     
         15 . The system of  claim 1 , wherein the hydrocarbon source comprises an engine. 
     
     
         16 . The system of  claim 1 , wherein the hydrocarbon source comprises a fuel injector. 
     
     
         17 . The system of  claim 1 , further comprising a reductant injector upstream of the SCR catalyst. 
     
     
         18 . The system of  claim 1 , wherein the system is durable to high hydrocarbon exposure.